\begin{tikzpicture}
    \tkzDefPoints{0/0/O}
    \tkzDefPoint(55:1.5){A}
    \tkzDefPoint(255:1.5){B}
    \tkzDefPoint(330:1.5){C}
    \tkzDefPoint(235:1.5){D}

    \tkzDrawCircle[thick](O,A)
    \tkzDrawPolygon(A,B,O,C)
    \tkzDrawSegment[dashed](A,D)
    \tkzLabelPoints[left](O)
    \tkzLabelPoints[above right](A)
    \tkzLabelPoints[right](C)
    \tkzLabelPoints[below](B)
    \tkzLabelPoints[below left](D)
\end{tikzpicture}

